Method of Utilization of Gas Expansion Energy and Utilization Power Installation for Implementation of this Method

ABSTRACT

A method and installation are provided for reduction of natural gas from high pressure, such as in a borehole or in a main pipeline down to the pressure valve required for the consumer.

RELATED APPLICATIONS

The present invention is a continuation in part of U.S. Ser. No.10/344,486, which was a National Phase Application based uponPCT/RU2001/00351.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The proposed method and the installation are intended for application insystems of reduction of natural gas from high—e.g. in the borehole or inmain pipelines down to the pressure value required for the consumer.

2. Description of the Related Art

The known methods of reduction of pressure of gas in boreholes or inmain pipelines are based on throttling and using special devices(pressure regulators, valves, cocks etc) for implementation of thesemethods. [Polytechnic Dictionary, Moscow, “Sovetskaya Entsiklopedia”Publishing House, 1977, pp. 153, 420]

These methods and devices for implementation thereof do not utilizeenergy of gas expansion and cold generated during this process. Theapplication of these methods and devices requires sophisticatedequipment and consumption of additional power to prevent clogging ofpressure regulators by moisture and ice generated during theiroperation.

A method of utilization of energy of natural gas when its pressure dropsfrom the value in the main pipeline or in the borehole down to therequired pressure by conversion of gas expansion energy to mechanicalenergy is known. RU 2117173, IPC 6 F 02 C 1/02, 1996]. This method isimplemented in a utilization power installation the inlet of which isconnected to the outlet of the high pressure gas borehole or the mainpipeline and the outlet—to the low pressure gas pipeline or to the gasconsumer. This utilization power installation includes a gas expansionmachine, e.g. an expansion turbine, and a mechanical energy converterconnected kinematically with the gas expansion machine, e.g. an electricgenerator. Such method and the installation make it possible to utilizegas expansion energy when its pressure drops.

However this method and the installation do not provide the possibilityof utilization of cold generated in the process of gas expansion. Theefficiency of this method and the installation is low.

There is a method of utilization of gas expansion energy when the gaspressure drops from a high value to the required one by conversion ofgas expansion energy to mechanical energy with simultaneous utilizationof the gas cooled down during pressure drop as a cooling agent forgeneration of cold. [SU, A1, 844797]

However this method provides a single-stage gas pressure drop and hencetotal efficiency thereof is reduced.

There is a power installation for utilization of gas expansion energyand the cold generated during this process. [RU 2013616, IPC F 02 C6/00, 1994]

However efficiency of this installation is low as gas pressure reductionand utilization of cold are effected at a single stage.

SUMMARY OF THE INVENTION

The object of this invention is to improve utilization of cold generatedduring the process of reduction of natural gas pressure; generation ofgreat amount of energy and cold and to increase total efficiency of themethod and the installation for utilization of natural gas expansionenergy.

The problem set in the proposed method is solved by reduction of naturalgas from high—e.g. in main pipelines down to the pressure value requiredfor the consumer by conversion of gas expansion energy to mechanicalenergy by using the gas cooled down in the process of gas pressure dropas a cooling agent. The innovation of this method is reduction ofnatural gas pressure in two or more successive stages and simultaneousutilization of at least a part of gas after the first and/or after eachrespective subsequent stage of reduction of natural gas pressure as acooling agent for generation and use of cold. Another part of naturalgas after the first and/or after each respective subsequent stage ofreduction of natural gas pressure or the total amount of natural gasused as a cooling agent is used at the next stage of conversion ofnatural gas expansion energy to mechanical energy.

Due to application of the stage-by-stage reduction of natural gaspressure and the use of the total amount or a part of natural gas afterthe first and/or after the relevant subsequent stage of natural gaspressure drop the total efficiency of the method increases.

The problem set in the proposed machine is solved by implementation of ainstallation for utilization of natural gas expansion energy thatincludes a gas expansion machine, e.g. an expansion turbine, inlet ofwhich is connected to a high pressure gas borehole or main pipeline andthe outlet—to a low pressure gas pipeline; a gas expansion machine, e.g.an expansion turbine and a mechanical energy converter connectedkinematically with the gas expansion means, e.g. an electric generator.There is at least one heat exchanger in this installation, the outletbranch pipe of which is connected to the outlet of the gas expansionmachine, e.g. to the outlet of the expansion turbine.

The innovation introduced in this facility is that the gas expansionmachine of the utilization power installation, e.g. the expansionturbine, consists of two or more gas expansion machines arranged in thedirection of natural gas pressure drop; the installation also comprisestwo or more heat-exchangers—refrigerators; the inlet branch pipe fromthe coolant side of each heat-exchanger—refrigerator is connected to theoutlet of the relevant gas expansion machine and the number ofheat-exchangers—refrigerators is not less than the number of expansionmachine components.

This improvement of the utilization power installation ensures theincrease of efficiency of this installation and the amount of generatedcold.

The outlet of the preceding component of the gas expansion machine ofthe utilization power installation can be connected simultaneously bothto the inlet of the next component of the gas expansion machine, and tothe inlet branch pipe from the cooling agent side of the relevant heatexchanger-refrigerator, and the outlet branch pipe from the coolingagent side of one or more heat exchanger-refrigerators—to the lowpressure gas pipeline or the gas consumer. In this case the flow of theworking medium branches out and a part of the working medium is takenoff for utilization of cold. This improves the thermo-dynamical workingcycle of the installation.

Such an improvement increases the efficiency of the installation. At thesame time it becomes possible to optimally regulate the operation of thegas expansion machine when the operation mode changes.

In the utilization power installation proposed the outlet of thepreceding component of the gas expansion machine can only be connectedto the inlet branch pipe from the cooling agent side of one or each heatexchanger-refrigerator, located between two components of the gasexpansion machine, and the outlet branch pipe from the cooling agentside of the same heat exchanger-refrigerator, located between the twocomponents of the gas expansion machine, can be connected to the inletof the working medium of the next component of the gas expansionmachine. Then additional heating of the working medium (gas) occurs inone or in each heat exchanger-refrigerator. It improves thermo-dynamicalworking cycle of the installation.

This improvement increases additionally the efficiency of theinstallation and by utilization of the heat of the cooling agent, heateddue to heat exchange in the heat exchanger-refrigerator. At the sametime it becomes possible to optimally regulate the operation of the gasexpansion machine when the operation mode changes by changing the amountand/or the temperature of the working medium (liquid, gas or severalworking mediums) heated in the heat exchangers-refrigerators.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will become betterunderstood with reference to the following more detailed description andclaims taken in conjunction with the accompanying drawings, in whichlike elements are identified with like symbols, and in which:

FIG. 1 the diagram of a utilization power installation is shown. Theinstallation includes an expansion gas turbine that contains a highpressure component and a low pressure component, two heatexchangers-refrigerators and an electric generator;

FIG. 2 the diagram of a utilization power installation is shown; theinstallation includes an expansion gas turbine that contains a highpressure component, a medium pressure component and a low pressurecomponent, three heat exchangers-refrigerators and an electricgenerator;

FIG. 3 the diagram of a utilization power installation is shown. Theinstallation includes expansion gas turbines that contain high pressurecomponents, medium pressure components and low pressure components,three heat exchangers-refrigerators and three electric generators.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The best mode for carrying out the invention is presented in terms ofits preferred embodiment, herein depicted within the Figures

1. Detailed Description of the Figures

The invented method and the installation are illustrated by descriptionsof the preferred embodiments thereof the embodiments of implementationof the utilization of gas expansion energy being described in thedisclosure of operation of variants of the installation.

As shown in FIG. 1, the utilization power installation includes anexpansion gas turbine that contains high pressure components 1 (HPM 1),and low pressure components 2 (LPM 2) arranged co-axially. The inlet ofHPM 1 is connected to high pressure gas main pipeline 3. This mainpipeline 3 can be a high- or medium-pressure natural gas pipeline, a gaspipeline of the gas distribution station, a thermal power station, aboiler house, a borehole in the natural gas production site etc. (Thesefacilities are not shown in the drawings). Electric generator shaft 4that supplies electric power to consumer 5 is connected kinematically ordirectly to the common shaft of HPM 1 and LPM 2. The outlet of HPM 1 isconnected both to the inlet of LPM 2, and the inlet branch pipe from thecooling agent side of heat exchanger-refrigerator 6. The outlet of thebranch pipe from the cooling agent side of heat exchanger-refrigerator 6is connected to the low pressure gas pipeline through which gas issupplied to consumer 7.

Heat exchanger-refrigerator 8 is installed at the gas outlet of LPM 2 ofthe expansion gas turbine. The inlet branch pipe of the heatexchanger-refrigerator from the cooling agent side is connected to thegas outlet out of LPM 2 of the expansion gas turbine and the outletbranch pipe from the cooling agent side of the heatexchanger-refrigerator 8 is connected to the low pressure gas pipeline,that supplies gas to consumer 9.

The utilization power installation operates in the following way. Highpressure natural gas flows out of main pipeline 3 into HPM 1, rotatesthe same expanding and cooling at the same time. A part of this naturalgas flows into LPM 2, another part—into the inlet branch pipe from thecooling agent side of heat exchanger-refrigerator 6. Partially cooleddown gas under partially reduced pressure passes through heatexchanger-refrigerator 6. Next the natural gas under required pressureis supplied to gas consumer 7.

Another part of gas that was delivered into LPM 2 of the expansion gasturbine performs additional work, reduces pressure and is cooled down.This gas is fed from LPM 2 to the second heat exchanger-refrigerator 8,where gas is heated and cold is taken off. Next natural gas underreduced pressure is supplied to consumer 9. The expansion gas turbinethat includes HPM 1 and LPM 2 rotates electric generator electricgenerator 4. Electric power is supplied to consumer 5.

Cold can be used for freezing chambers, ice rinks etc and forliquefaction of natural gas produced from boreholes. The useful workperformed by gas in the process of expansion can also be used forliquefaction of gas and power supply of a remote natural gas borehole.

According to FIG. 2, utilization power installation includes anexpansion gas turbine that contains high pressure component 10 (HPM 10),medium pressure component 11 (MPC 11) and low pressure component (LPM12) that are arranged on the same shaft. The inlet of HPM 10 isconnected to high pressure gas main pipeline 13. The outlet of HPM 10 isconnected both to the inlet of MPC 11 and to the inlet branch pipe fromthe cooling agent side of heat exchanger-refrigerator 16. The gas outletof heat exchanger-refrigerator 16 is connected to low pressure gasconsumer 17. The outlet of MPC 111 is connected both to the inlet of LPM12 and the inlet branch pipe from the cooling agent side of heatexchanger-refrigerator 18. The gas outlet from heatexchanger-refrigerator 18 is connected to low pressure gas consumer 19.The outlet of LPM 12 is connected to the inlet branch pipe from thecooling agent side of heat exchanger-refrigerator 20. The gas outletfrom heat exchanger-refrigerator 20 is connected to low pressure gasconsumer 21.

The utilization power installation operates in the following way. Highpressure natural gas flows out of main pipeline 13 into HPM 10, rotatesthe same expanding and cooling at the same time. A part of this naturalgas flows into MPC 11, rotates the same expanding and cooling at thesame time, another part—into the inlet branch pipe from the coolingagent side of heat exchanger-refrigerator 16, from which natural gas issupplied to low pressure gas consumer 17. Pressure required to gasconsumer 17 can be higher than that required to other natural gasconsumers 19 and 21. Another part of the gas flow performs work in MPC11, reduces pressure additionally and is cooled down. Next natural gasflow branches out. One part of this flow is fed to the inlet branch pipefrom the cooling agent side of heat exchanger-refrigerator 18, fromwhich natural gas is supplied to gas consumer 19. The rest part of theflow is fed to the inlet of LPM 12, rotating the same expanding andbeing cooled down at the same time. Then natural gas flows into heatexchanger-refrigerator 20, from which it is fed to low pressure naturalgas consumer 21. The expansion gas turbine rotates electric generator14, that generates current for electric power consumer 15.

Cold can be used for freezing chambers, ice rinks etc and forliquefaction of natural gas produced from boreholes. The useful workperformed by gas in the process of expansion can also be used forliquefaction of gas and power supply of a remote natural gas borehole.

Referring now to FIG. 3, the utilization power installation includeshigh pressure expansion gas turbine 22 (HPT 22), the inlet of which isconnected to high pressure natural gas pipeline 23. The shaft of HPT 22is connected to electric generator 24 kinematically or directly thegenerator being electrically connected with power consumer 25. Theoutlet of HPT 22 is connected to the inlet branch pipe from the coolingagent side of heat exchanger-refrigerator 26. The gas outlet of heatexchanger-refrigerator 26 is connected to the inlet of the mediumpressure expansion gas turbine 27 (MPT 27). The shaft of MPT 27 isconnected kinematically or directly to electric generator 28, which isconnected electrically to power consumer 29. The outlet of MPT 27 isconnected to the inlet branch pipe from the cooling agent side of heatexchanger-refrigerator 30. The gas outlet of heat exchanger-refrigerator30 is connected to the inlet of low pressure expansion gas turbine 31(LPT 31). The shaft of LPT 31 is connected kinematically or directly toelectric generator 32, which is connected electrically with powerconsumer 33. The outlet of LPT 31 is connected to the gas inlet of heatexchanger-refrigerator 34. The gas outlet of the heatexchanger-refrigerator 34 is connected to low pressure natural gasconsumer 35.

The utilization power installation operates in the following way. Highpressure natural gas is fed from main pipeline 23 to HPT 22, rotatingthe same, expanding and being cooled down. Next gas is supplied from HPT22 to heat exchanger-refrigerator 26, where cold is utilized and gas isheated and expands. Further gas is delivered to MPT 27, rotating thesame, expanding and being cooled down. Next gas flows into heatexchanger-refrigerator 30, where cold is utilized and gas is heated andexpands. Then heated and expanded gas is fed from heatexchanger-refrigerator 30 to LPT 31 rotating the same, expanding andbeing cooled down. Next gas flows from LPT 31 to heatexchanger-refrigerator 34, where cold is utilized and natural gas isheated and expands. Further natural gas is supplied to low pressure gasconsumer 35. HPT 22, MPT 27 and LPT 31 rotate electric generators 24, 28and 32 respectively that supply electric power to consumers 25, 29, 33.Electric generators 24, 28 and 32 can be connected to the commonelectric network

Due to stage-by-stage cooling down of gas in HPT 22, MPT 27 and LPT 31and stage-by-stage heating of the same in heat exchangers-refrigerators26 and 30 total efficiency of utilization power installation increases.

2. Operation of the Preferred Embodiment

The invention can be used for solving a wide scope of practical problemsof generation of additional energy and non-expensive cold. The inventioncan be used at the outlet of high pressure natural gas directly out ofboreholes and for reduction of gas pressure at the outlet of mainpipelines down to the pressure required by the consumer etc.

In all descriptions of preferred embodiments an expansion gas turbine isused as a gas expansion machine. However a gas expansion machine of anytype can be used, e.g. piston or rotor—type gas expansion machines,including those comprising high pressure and low pressure components orhigh pressure, medium pressure and low pressure components. Turbines,pumps, ventilators, winches or other converters of mechanical energy canbe used instead and/or simultaneously with the electric generator.

Utilization power installations described in preferred embodiments ofthe invention utilization power installations can be located directlybeside natural gas boreholes if natural gas pressure at the outlet ofthe borehole exceeds pressure required for the gas main pipeline. Inthis case cold can be used for liquefaction of natural gas produced. Theuseful work performed by gas in the process of expansion can be used forliquefaction of gas power supply of a remote natural gas borehole. Theutilization power installations proposed are very efficient in placeswhere gas main pipelines are connected to installations for natural gassupply to big consumers (electric power plants, domestic natural gasnetworks in settlements etc).

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the claims appended hereto and theirequivalents. Therefore, the scope of the invention is to be limited onlyby the following claims.

1. A method of utilization of the natural gas expansion energy duringthe process of reduction of gas pressure from high pressure to therequired pressure by converting the natural gas expansion energy tomechanical energy, with the gas cooled down in the process of pressurereduction being used as a cooling agent for generation of cold,comprising the steps: a. Reducing the natural gas pressure in more thanone successive stages simultaneously with conversion of natural gasexpansion energy to mechanical energy at each stage; and b. Using atleast a part of natural gas as a cooling agent for generation of coldafter each stage of natural gas pressure drop.
 2. A power installationcomprising: a gas expansion means consisting of more than one gasexpansion machine arranged in the direction of natural gas pressuredrop; at least one converter of mechanical energy having a rotor beingconnected kinematically with the rotor of at least one gas expansionmachine; exchangers-refrigerators being not less than the number of thegas expansion machines; and wherein the first of the gas expansionmachine has an inlet being connected to a high pressure natural gassource; the outlet of a preceding gas expansion machine is connectedonly to the inlet branch pipe on the cooling agent side of theexchanger-refrigerator, and the outlet branch pipe on the cooling agentside of at least one exchanger-refrigerators is connected to the inletof at least one gas expansion machine.
 3. A power installationcomprising: a gas expansion means comprising a high pressure gasexpansion machine and a low pressure gas expansion machine, the inlet ofthe high pressure gas expansion machine being connected to a highpressure natural gas source; wherein said high pressure gas expansionmachine has an inlet and an outlet, and said low pressure gas expansionmachine has an inlet and an outlet; a converter of mechanical energyhaving a rotor being connected kinematically with the rotor of at leastone gas expansion machine; a first exchanger-refrigerator; the outlet ofthe high pressure gas expansion machine is connected only to the inletbranch pipe on the cooling agent side of the firstexchanger-refrigerator; and the outlet branch pipe on the cooling agentside of the exchanger-refrigerator is connected to inlet of the lowpressure gas expansion machine.
 4. The power installation of claim 2,further comprising an exchanger-refrigerator installed at the outlet ofthe low pressure gas expansion machine.
 5. The power installation ofclaim 4, wherein the inlet branch pipe of the exchanger-refrigerator onthe cooling agent side is connected to the outlet of the low pressuregas expansion machine and the outlet branch pipe the cooling agent sideof the exchanger-refrigerator is connected to the low pressure naturalgas machine.
 6. The power installation of claim 2, wherein the rotors ofthe gas expansion machines are kinematically unconnected with eachother, the rotor of each gas expansion machine is kinematicallyconnected with the rotor of a converter of mechanical energy.
 7. Thepower installation of claim 2, wherein the high pressure natural gassource is selected from the group comprising: a main pipeline, a highpressure natural gas pipeline, a medium pressure natural gas pipeline, agas pipeline of a gas distribution station, a gas pipeline of a powerstation, a boiler house and a borehole of a natural gas production site,etc.
 8. The power installation of claim 3, wherein the high pressurenatural gas source is selected from the group comprising: a mainpipeline, a high pressure natural gas pipeline, a medium pressurenatural gas pipeline, a gas pipeline of a gas distribution station, agas pipeline of a power station, a boiler house and a borehole of anatural gas production site, etc.
 9. The power installation of claim 2further comprising an exchanger-refrigerator installed at the outlet ofthe low pressure gas expansion machine.
 10. The power installation ofclaim 3 further comprising an exchanger-refrigerator installed at theoutlet of the low pressure gas expansion machine.
 11. The powerinstallation of claim 3, wherein the rotors of the gas expansionmachines are kinematically unconnected with each other, the rotor ofeach gas expansion machine is kinematically connected with a rotor ofconverter of mechanical energy.
 12. The power installation of claim 2,wherein the rotors of the gas expansion machines are kinematicallyconnected with each other, the rotor of each gas expansion machine arekinematically connected with a rotor of converter of mechanical energy.13. The power installation of claim 3, wherein the rotors of the gasexpansion machines are kinematically connected with each other, therotors of each gas expansion machine is kinematically connected withrotors of converter of mechanical energy.
 14. The power installation ofclaim 2, wherein the rotors of the gas expansion machines arekinematically connected with each other, the rotors of each gasexpansion machine is kinematically connected with rotor of at least oneconverter of mechanical energy.
 15. The power installation of claim 3,wherein the rotors of the gas expansion machine are kinematicallyconnected with each other, the rotors of each gas expansion machine iskinematically connected with a rotor of at least one converter ofmechanical energy.
 16. The improvement of the power installationaccording to claim 3, wherein the rotors of the Gas expansion machine iskinematically unconnected with each other; the rotors of each the gasexpansion machines are kinematically connected with at least one rotorof converter of mechanical energy.
 17. The improvement of the powerinstallation according to claim 3, wherein the rotors of the gasexpansion machines are mechanically unconnected with each other; therotor of each the gas expansion machines is mechanically connected withrotor of converter of mechanical energy.
 18. The improvement of thepower installation according to claim 3, wherein the rotors of the gasexpansion machines are mechanically connected with each other; the rotorof the gas expansion machines is mechanically connected with rotor of atleast one converter of mechanical energy.
 19. An improvement of thepower installation according to claim 3 wherein the rotors of the gasexpansion machines are kinematically connected with each other; therotors of the gas expansion machines are kinematically connected with aconverter of mechanical energy.
 20. An improvement of the powerinstallation according to claim 3 wherein the rotors of the gasexpansion machines are kinematically connected with each other; therotors of the gas expansion machines are kinematically connected withrotor of at least one converter of mechanical energy.
 21. An improvementof the power installation according to claim 3 wherein the rotors of thegas expansion machines are mechanically connected with each other; therotors of the gas expansion machines are mechanically connected withrotor of at least one converter of mechanical energy.